Understanding and Managing Pecan Bacterial Leaf Scorch Southeastern - - PowerPoint PPT Presentation
Understanding and Managing Pecan Bacterial Leaf Scorch Southeastern Pecan Growers Association Convention Destin, Florida February 26-27, 2016 Rebecca A. Melanson , Extension Plant Pathologist Central MS Research and Extension Center
Southeastern Pecan Growers Association Convention Destin, Florida • February 26-27, 2016 Rebecca A. Melanson, Extension Plant Pathologist Central MS Research and Extension Center • Raymond, MS
tissues (xylem) of the plant PBLS in ‘Cape Fear’ pecan.
Late-stage PBLS symptoms. ‘Early’-stage PBLS symptoms.
PBLS in a mature tree. PBLS in a young grafted tree.
Reference: Sanderlin, 2005, Plant Disease 89:446-449.
*Highly susceptible cultivars.
Time Period % Leaflet Defoliation % Reduced Kernel Weight % Reduced Nut Weight Year 1 67 19 29 Year 2 66 16 32 Year 3 41 14 20 Average 58 16.3 27 Age of Trees % Less Diameter % Less Height 4 Years Old 43 40 9 Years Old 52 N/A
References: Sanderlin and Heyderich-Alger, 2003, Plant Disease 87(3):259-262.; Sanderlin, unpublished
PBLS in new growth from infected scion.
References: Sanderlin and Melanson, 2008, Plant Disease 92:1124-1126.; Sanderlin and Melanson, 2006, HortScience 41(6):1455-1456.
Prepared scions for storage. Submerged scions in hot water. Grafted to non-infected rootstock. Identified PBLS-infected limbs.
Bundled scions with a weight.
water for 1-2 min Completely submerge!
The link to the publication “Procedure for Hot Water Treatment of Pecan Scion Wood” can be found at the end of this presentation.
Two-Year Totals # of Scions Tested % Graft Success # of Trees with PBLS Symptoms # of X. fastidiosa- Infected Trees Hot-water Treated Scions
165 84.8 2 1
Non-treated Scions
105 84.7 18 19 0.7 21.3
20 40 60 80 100
Hot-water-treated scions Non-treated scions % Graft-transmission of X. fastidiosa
At a 21% graft-transmission rate, 29 of the 140 hot- water-treated scions should have been infected. **97% EFFECTIVE**
Reference: Sanderlin and Melanson, 2008, Plant Disease 92:1124-1126.
– 3 cultivars and non- grafted trees – 5 rootstocks Year Number of Diseased Trees/Number of Trees in Orchard (% Infected Trees) 2001 5/410 (1.2%) 2002 12/410 (2.9%) 2003 17/409 (4.2%) 2004 33/390 (8.5%) 2005 63/390 (16.2%) 2006 91/390 (23.3%)
An increase in the number of PBLS-infected trees was
However, the greatest increase in the number of infected trees occurred in cultivar Cape Fear, the cultivar in the
Fed captured insects on infected pecan tissue and then caged them
Collected potential vectors – xylem-feeding insects (spittlebugs and sharpshooters).
Lateral-lined sharpshooter Johnsongrass sharpshooter Diamond-backed spittlebug Glassy-winged sharpshooter Pecan spittlebug (adult) Photos by: S. Gil Photo by: R. Melanson 2 – 11.4% 100% 19.6% 16.7% 4%
Reference: Sanderlin and Melanson, 2010, Plant Disease 94(4):465-470.
Pecan Research-Extension Station in Shreveport, LA, has monitored five pecan
known and potential vectors of Xylella fastidiosa using yellow sticky traps. Data indicated that the greatest number of known and potential vectors were present in
Orchard locations:
*Known and potential vectors
– Almond, grapevine
– Almond, peach, oak, pecan
– Citrus, coffee
– Oleander
– Chitalpa
Pierce’s disease
Citrus variegated chlorosis*
Bacterial leaf scorch in pin oak
Bacterial leaf scorch in sycamore
*Not currently present in the U.S.
during peak trapping periods or at first appearance (?)
attract vectors OR manage vectors on those plants (?)
Extension Plant Pathologist Central Mississippi Research and Extension Center Mississippi State University Phone: (601) 857-2284 Email: rebecca.melanson@msstate.edu
Research/Extension Plant Pathologist LSU AgCenter Pecan Research-Extension Station Louisiana State University Email: RSanderlin@agcenter.lsu.edu
Photo by MSU Extension
The research discussed in this presentation was conducted by
Pecan Research-Extension Station or at Louisiana State
by R. A. Melanson or R. S. Sanderlin.
– Pecan Bacterial Leaf Scorch Cultivar Susceptibility and Pathogen Transmission – Pecan Bacterial Leaf Scorch: A New Look at an Old Problem – Procedure for Hot Water Treatment of Pecan Scion Wood
– www.ipmimages.org/
Xylella fastidiosa, the causal agent of pecan bacterial leaf scorch, into orchards and new geographic regions. Acta Horticulturae 1070:201-209.
part of X. fastidiosa subsp. multiplex. Plant Disease 96:1123-1134.
Disease 92:1124-1126.
Disease 87(3):259-262.
1282-1286.